In machines having a cyclic operation, as in an internal combustion engine, certain operations or certain movements must be controlled or actuated in synchronism with the displacement or rotation of a part such as the crankshaft. For example, the occurrence of spark ignition, fuel injection, and movement of a valve, must be coordinated. One of the known difficulties is to mount a position sensor so that it has a fixed, known position with respect to a reference position of the moving engine. When an engine position is established so that the number one cylinder has a piston at top dead center, the distributor can be mounted on the engine so that the position sensor indicates the engine's position. However, such mounting is typically subject to a mechanical mounting error.
For example, U.S. Pat. No. 3,517,142 to Hans-Dieter Bastam et al teaches a typical mechanical connection where a signal generator assembly is mounted on a distributor shaft and cooperates with two pivotable contacts. U.S. Pat. No. 4,235,213 to Jellissen teaches an ignition system housing to provide timing signals fo an automotive ignition distributor system. A housing is mounted on a swing arm. The housing is fixed in position and locked in place by screws engaged in the threaded central bores of the housing. The housing is attached to the swing arm by having bosses positioned within the cavities.
In the systems taught in both these patents, the errors inherent in such mechanical mountings of the signal generating circuit reduce the correlation between the actual position of the engine and the indicated position to the engine. These are some of the problems this invention overcomes.